Some applications have a large two dimensional (2D) array of switches implemented with phase change material (PCM). In order to change the state of a large 2D PCM array in a fast manner a large number of switches may have to be nearly simultaneously switched from one state to the other state.
The operating mode of phase change materials is based on a change in electronic and optical properties that occurs with a rearrangement in the microscopic structure from a crystalline to an amorphous phase. The electrical conductivity can change by several orders of magnitude upon the phase transition, while the optical reflectivity changes depending on layer thickness and wavelength. Furthermore, phase change materials can be rapidly switched between the crystalline and amorphous phases.
To change the state of a 2D array of PCM switches, a set or reset pulse needs to be sent to each PCM switch. Setting or resetting a PCM switch may be referred to as writing the switch, and when a PCM switch is set or reset that may be referred as the PCM switch being written. When the set or reset pulse is sent to a particular PCM switch, heat is generated at the PCM switch. If two PCM switches are sent a set or reset pulse at the same time, another PCM switch that is adjacent to the two PCM switches and that has not been sent a set or reset pulse and whose state should not be changed, may be inadvertently switched by the heat generated by the adjacent PCMs being switched. This inadvertent and unwanted switching of an adjacent switch is quite undesirable, and can lead to improper operation of an infrared spatial light modulator (ISLM).
What is needed is an improved apparatus and method that avoids such inadvertent and unwanted switching. The embodiments of the present disclosure answer these and other needs.